Area navigation system for automatically selecting waypoints on the track and lying at a right angle from a master station

ABSTRACT

An area navigation system which provides for the automatic selection of waypoints on the track at a point which is at right angles from the track to the master station. Means are provided for determining the distance from the aircraft to the waypoint and the distance of the waypoint from the master station and these signals are utilized to automatically set the coordinates of the waypoint into the area navigation equipment.

United States Patent Perkins [4 1 Sept. 12, 1972 [54] AREA NAVIGATIONSYSTEM FOR [56] References Cited AUTOMATICALLY SELECTING WAYPOINTS ONTHE TRACK AND UNITED STATES PATENTS L I A A RIGHT ANGLE FRQM A 3,534,39910/1970 Hirsch ..235/l50.27 MASTER STATION 3,581,073 5/1971 Visher..235/150.26 [72] Inventor: Carl Stuart Perkins, Oak Brook, 111. p i pli Gruber [73] Assign; Butler National Comma!!! o Attorney-Hill,Sherman, Meroni, Gross & Simpson 57 ABSTRACT 22 F1 97 l l ed Nov l 0 Anarea navigation system which provides for the au- PP 4 tomatic selectionof waypoints on the track at a point which is at right angles from thetrack to the master station. Means are provided for determining the [52]gifi2 3 5:; g :5 distance from the aircraft to the waypoint and the 51 It. G06 7/78 distance of the waypoint from the master station and E g 26these signals are utilized to automatically set the coor- 235/150.26l,150.27; 343/107, 112 D, 112 C, 112 R M AYPO/NT BEAR/N6 R6504 Veg dinatesof the waypoint into the area navigation equipment.

7 Claims, 2 Drawing Figures 5 YMCA/ 0 r 75M TKACK a R5501. v52

52 72 .54 057 2 17/455 REF,

PATENTED SEP 12 1972 BY ATTORNEYS v CROSS-REFERENCE TO RELATEDAPPLICATIONS AND PATENTS This invention is related to US. Pat. No.3,414,901 entitled AIRCRAFT NAVIGATION SYSTEM and to co-pendingapplications of EARL STUART PERKINS entitled AUTOMATIC WAYPOINT, Ser.No. 824,164 filed May 13, 1969 now US. Pat. No. 3,652,873 and AUTOMATICTRACK, Ser. No. 816,302 filed April 15, l969,nowPat. No. 3,621,211.

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates in general to aircraft navigation systems and in particular toarea navigation systems.

2. Description of the Prior Art Area navigation systems in which a pilotmay select any point as a waypoint rather than being limited tolocations which have navigation transmitting facilities have recentlycome into use as shown for example by US. Pat. No. 3,414,901. Co-pendingapplication Ser. No. 816,302 provides for automatic servo control of theco-ordinates of a waypoint such that the present position of an aircraftis continuously maintained as the waypoint until such time that it isdesired to fix the waypoint after which the fixed waypoint is utilizedas the reference in the navigation system.

Co-pending application Ser. No. 824,164 provides for fixing a waypointonthe present track of the aircraft at a fixed distance as of the time ofselection. For example, the waypoint might be 150 miles ahead of theaircraft on the track at the time that the waypoint is selected and thearea navigation system will then indicate the distance to the waypointas the aircraft passes down the track.

SUMMARY OF THE INVENTION The present invention provides a system forautomatically selecting a waypoint in an area navigation system whichcomprises a point on the track of the aircraft which is located on aradial from the station which is at right angles to the track. Suchwaypoint identified as the perpendicular waypoint allows the distance tothe nearest point to the ground station to be indicated in the areanavigation system at all times and can be utilized as the prime waypointfor each station and allows Great Circle paths or parallels thereto tobe traveled over the surface of the earth.

The co-ordinates of the perpendicular waypoint" are determined from theVCR bearing of the aircraft to the station and from the track angle andthe distance of the aircraft from the station. These coordinates allowthe p9 setting of the perpendicular waypoint to be automatically setinto the area navigation system so that the pilot may continuouslymonitor his position relative to the perpendicular waypoint.

Other objects, features and advantage of the invention will be apparentto those skilled in the art from the following description of theannexed sheet of drawings which by way of a preferred embodiment of theinvention will illustrate one example of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram illustratingthe apparatus for automatically establishing the perpendicular waypoint;and

FIG. 2 is a plan view illustrating the orientationing of the aircraft,the master station and the perpendicular waypoint.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 illustrates an areanavigation system according to this invention which also includes theautomatic waypoint feature which allows the automatic selection of aperpendicular waypoint. The perpendicular waypoint is defined as thepoint along a track which an aircraft is travelling which 'is on aradial of the master station which crosses the track at right angles.The advantage of utilizing this point is that it can become the primewaypoint for each station and is the closest point of a track parallelto the Great Circle through the station.

The conventional portion of the area navigation system of the inventioncomprises the DME receiver 10 and VCR receiver 1 1 which provide outputsto an OBI resolver 12 which resolves the distance and direction signalsto the navigation station into Cartesian coordinate signals which appearat the output of the OBI resolver. These outputs are respectivelysupplied to summing amplifiers 13 and 14 which also receive Cartesiancoordinate signals from the waypoint bearing resolver 32. The waypointbearing resolver 32 has a control shaft 43 with a knob 33 for settingthe coordinates of a waypoint which has a particular bearing from thestation. An indicator 34 indicates the selected bearing of the waypointfrom the station. A waypoint distance potentiometer 36 includes apotentiometer 37 with a wiper contact 38 which may be set by a shaft 41by a knob 39 to a particular coordinate of the waypoint indicated as pin FIG. 2. An indicator 42 indicates the p coordinate of the waypoint.The output signal of the waypoint distance potentiometer is supplied tothe waypoint bearing resolver. The output of the summing amplifiers 13and 14 are supplied respectively through switches S5 and S6 to the trackresolver 16. The track resolver 16 has a track selecting shaft 28 whichmay be controlled by the knob 27 to establish a selected track. Anindicator 31 indicates the selected track. A heading synchro 24 isconnected to the shaft 28 and receives an input from a compass system26. An area navigation indicator 17 has a pair of meter movements 71 and72. The meter movement 71 receives the y output of the track resolver 16and the meter movement 72 receives the x output of the track resolver16. A horizontal needle 21 is controlled by the meter movement 71 and avertical needle 22 is controlled by the meter movement 72. Fixed indicia18 and 19 are printed on the face of the indicator 17 for referencepurposes. An aircraft indicia 23 is rotatably supported at the center ofthe indicator 17 and is positioned by the output of the heading synchro24. For simplicity the aircraft indicia 23 is shown above the indicator17 rather than mounted at the center.

The system described so far comprises a conventional area navigationsystem such as described for example in US. Pat. No. 3,414,901. Theimprovement of the present invention comprises providing a servo motor46 which is connected to the shaft 41 of the waypoint distancepotentiometer 36 to move the wiper contact 38 and which receives aninput from a servo amplifier 44. The servo amplifier 44 receives aninput from the sign detector and resolver 49. A switch S1 when closedprovides the y output of the track resolver 16 to the servo amplifier 44through the switch S1 and sign detector and resolver 49. A feedbacksignal is also applied to the servo amplifier 44 through a switch S2from the wiper contact 38 of the waypoint distance potentiometer 36.

A servo motor 47 is connected to shaft 43 of the waypoint bearingresolver 32 and receives an input from the servo amplifier 48 whichreceives the x output of the track resolver 16 through switch S4. Servoamplifier 48 also receives an input through switch S3 from a signdetector phase reference 54 through lead 53. An RM I servo 57 suppliesan input to the sign detector and phase reference 54 and to a distanceto station servo 56. A switch S disconnects the track resolver from theoutput of the summing amplifier l3 and connects it to a contact 58 whichis connected to one of the outputs of the omni-bearing resolver 12.Switch S6 disconnects the track resolver 16 from the output summingamplifier l4 and connects the track resolver to a contact 59 which isconnected to the other output of the omnibearing indicator resolver 12.

When the switches 81-86 are in the position shown in FIG. 1, the areanavigation system operates in the conventional manner utilizing thewaypoint established and indicated in the indicators 42 and 34. When itis desired to automatically establish a waypoint which is along thetrack and lies on a radial from the radio station which crosses thetrack at 90, the switches 51-86 are moved to their second position suchthat switches S1, S2, S3, S4 close, the switches S5 and S6 move toengage contacts 58 and 59. When this occurs, the servo motors 46 and 47will automatically set the waypoint distance potentiometer 36 and thewaypoint bearing resolver 32 to the correct coordinates of theperpendicular waypoint.

The pilot allows the switches to remain in this position for selectingthe automatic waypoint until the indicators 42 and 34 remain stationarywhich indicates that the proper coordinates of the perpendicularwaypoint have been established and then moves the switches Sl-S6 back tothe positions indicated in FIG. 1, at which time the area navigationsystem will continuously indicate the aircrafts position relative to theperpendicular waypoint which has been established. It is to be realizedthat the switches Sl-S6 may be ganged together so that theysimultaneously are actuated by the pilot.

To understand the manner in which the perpendicular waypoint isestablished, reference may be made to FIG. 2. The aircrafts position isindicated relative to the radio station as having a VCR bearing d) and adistance aD as determined by the distance measuring receiver. Theaircraft is on a track a. The point on the track which is on a radial ofthe radio station which crosses the track at a right angle is identifiedas the perpendicular waypoint. The distance of the perpendicularwaypoint from the radio station is indicated by p. Thus theperpendicular waypoint coordinates of the perpendicular waypointrelative to the radio station is are defined by the coordinates pd). Theangle between the radial of the aircraft and the track is aand fromsimple trigometric operation p Dsin (a). DX is the distance from theaircraft to the perpendicular waypoint which is equal to Dcos (a).

The apparatus in FIG. 1, when switches S1, S2, S3 and S4 are closed andswitches S5 and S6 engage respectively contacts 58 and 59, producesoutput of the track resolver 16 of Dsin (a) on the output which goes tothe meter movement 71 and an output of Dcos (a) on the output which goesto the meter movement 72. The output to the meter movement 71 is equalto p as shown above and the servo motor 46 is driven by the servoamplifier 44 through the sign detector and resolver 49 and switch S1 toposition the p coordinate of the perpendicular waypoint to Dsin (aFeedback from the distance potentiometer wiper is applied to servoamplifier 44 through the switch S2. Thus the waypoint potentiometer willbe driven by the servo motor 46 to the correct value of p for theperpendicular waypoint.

At the same time, when the switches S1, S2, S3, s4 close and switches S5and S6 engage contacts 58 and 59, the RMI servo 57 produces an outputequal to DX, the distance from the aircraft to the perpendicularwaypoint, which is compared with the output Dcos (a-rp) from the trackresolver appearing on the output which goes to meter movement 72 in theservo amplifier 48 and the motor 47 is driven until the two inputs tothe servo amplifier are equal, thus, positioning the waypoint bearingresolver 32 to the correct coordinate data of the perpendicular waypointfrom the ground station R.S.

When the servos 46 and 47 come to a stop, the switches S1, S2, S3, S4are again opened and the switches S5 and S6 are moved out of engagementwith the contacts 58 and 59 to the position shown in FIG. 1 and the areanavigation system operates conventionally and continuously indicates theaircrafts position relative to the selected perpendicular waypoint.

Thus, it is seen that this invention allows the coordinates of aperpendicular waypoint on a track to be automatically selected withoutcalculation and the aircraft may then be flown relative to theperpendicular waypoint.

Although the invention has been described with respect to preferredembodiments, it is not to be so limited as changes or modifications maybe made which are within the full intent and scope as defined by theappended claims.

I claim as my invention:

1. A navigation system for a craft including:

an area navigation computer which incorporates track selecting means;

said computer receiving radiant energy from a ground station whichenergy is indicative of position and for computing signals correspondingto distance and bearing of a waypoint;

means for establishing signals indicative of distance and bearingcoordinates of a selected waypoint;

a first means selectively connected to said means for establishingsignals indicative of the bearing coordinate and receiving first andsecond output signals from said air navigation computer for changing thebearing coordinates so that the waypoint is caused to lie on theselected track; and

second means selectively connected to said means for establishing saiddistance coordinate signal and receiving a third output of said airnavigation computer for changing the distance coordinate signal of thewaypoint so that said waypoint is caused to lie on a bearing from saidground station which is at right angles to said selected track.

2. A navigation system according to claim 1 wherein said first andsecond output signals of said area navigation computer furnished to saidfirst means comprise a first signal proportional to the aircraftdistance to said waypoint and a second signal which is equal to aproduct of the distance of the aircraft to the ground station and thecosine of the angle equal to the difference between the selected trackangle and the bearing to said ground station.

3. A navigation system according to claim 1 wherein said third outputsignal of said area navigation computer furnished to said second meanscomprises a signal proportional to the product of the distance of theaircraft to the ground station and sine of the angle equal to thedifference between the track and the bearing to said ground station.

4. A navigation system according to claim 2 comprising first switchingmeans for connecting said first and second signals to said first means.

5. A navigation computer according to claim 3 comprising secondswitching means for connecting said third signal to said second means.

6. A navigation system according to claim 1 wherein said area navigationcomputer includes a track resolver and an omnibearing resolver and athird switching means for connecting the outputs of said omnibearingresolver to said track resolver when said first and second means areconnected to said means for establishing said bearing and distancecoordinates.

7. In a navigation system for a craft having an area navigationcomputer, the method of automatically defining a waypoint on a selectedtrack which lies on the right angle bearing from a ground stationcomprising the steps of:

l. generating signals indicative of distance and bearing coordinates ofa waypoint;

2. generating a signal corresponding to the bearing angle of a selectedtrack;

3. varying the distance coordinate signal of said waypoint until itequals the product of the distance to ground station signal and thesignal equal to the sine of the angle determined by the differencebetween the selected track and the bearing to said ground station; and

4. varying the bearing coordinate of said waypoint until the distance towaypoint is equal to the product of the distance of the craft to theground station and the cosine of the difference between the selectedtrack and the bearing to said ground station.

1. A navigation system for a craft including: an area navigationcomputer which incorporates track selecting means; said computerreceiving radiant energy from a ground station which energy isindicative of position and for computing signals corresponding todistance and bearing of a waypoint; means for establishing signalsindicative of distance and bearing coordinates of a selected waypoint; afirst means selectively connected to said means for establishing signalsindicative of the bearing coordinate and receiving first and secondoutput signals from said air navigation computer for changing thebearing coordinates so that the waypoint is caused to lie on theselected track; and second means selectively connected to said means forestablishing said distance coordinate signal and receiving a thirdoutput of said air navigation computer for changing the distancecoordinate signal of the waypoint so that said waypoint is caused to lieon a bearing from said ground station which is at right angles to saidselected track.
 2. generating a signal corresponding to the bearingangle of a selected track;
 2. A navigation system according to claim 1wherein said first and second output signals of said area navigationcomputer furnished to said first means comprise a first signalproportional to the aircraft distance to said waypoint and a secondsignal which is equal to a product of the distance of the aircraft tothe ground station and the cosine of the angle equal to the differencebetween the selected track angle and the bearing to said ground station.3. A navigation system according to claim 1 wherein said third outputsignal of said area navigation computer furnished to said second meanscomprises a signal proportional to the product of the distance of theaircraft to the ground station and sine of the angle equal to thedifference between the track and the bearing to said ground station. 3.varying the distance coordinate signal of said waypoint until it equalsthe product of the distance to ground station signal and the signalequal to the sine of the angle determined by the difference between theselected track and the bearing to said ground station; and
 4. Anavigation system according to claim 2 comprising first switching meansfor connecting said first and second signals to said first means. 4.varying the bearing coordinate of said waypoint until the distance towaypoint is equal to the product of the distance of the craft to theground station and the cosine of the difference between the selectedtrack and the bearing to said ground station.
 5. A navigation computeraccording to claim 3 comprising second switching means for connectingsaid third signal to said second means.
 6. A navigation system accordingto claim 1 wherein said area navigation computer includes a trackresolver and an omnibearing resolver and a third switching means forconnecting the outputs of said omnibearing resolver to said trackresolver when said first and second means are connected to said meansfor establishing said bearing and distance coordinates.
 7. In anavigation system for a craft having an area navigation computer, themethod of automatically defining a waypoint on a selected track whichlies on the right angle bearing from a ground station comprising thesteps of: